BIOL 1001 Lecture Notes - Lecture 2: Pitx1, Gene Duplication, Pseudogene
Take Notes
• Mechanical isolation : Two organism that have different mating rituals
• Errors sometimes occur when DNA duplicates itself : New genes can
enter the population and be acted upon by evolution.
• The human globin family contains several functional genes & several
pseudogenes (it looks like a functional gene, but it don’t produce
functional product) generated through gene duplication.
- Pseudogene : it looks like a functional gene, but it don’t produce
functional product
- Gene family : gene similar to each other in structure & function
duplicated genes = paralogs
1) Duplicated genes = paralogs
• Gene duplication can occur in mistake of DNA duplication or crossing
over(typical) --- It is in beginning of miosis,
• One homologous – missing gene , and the other – duplicating(gaining)
• * Why would gene duplication events such as those seen in the Hox gene
(it helps initial early embryo, which part should go ) complex, set the
stage for adaptive radiation? : D. one copy of a gene can perform the
original function while other copies are available to take on new function
2
Digestive enzymes modified to be antifreeze proteins.
• A duplicated gene is free from prior selection pressures.
1) Gene duplication could result in death
2) Mutation of duplicated gene could result in death
• Complex systems – e.g., enzyme-substrate relationships – can change
over time due to gene duplication --- protein function has changed over
time
• Potential phenotypic effects of duplications (might be abnormal – diff
than normal)
• Possible outcomes of gene duplication where duplication is not
deleterious
1) Duplicated genes retain original function → provide additional
quantities of same product = Not killing one – just get more same
product
2) May retain original function, but change in expression pattern (New
tissue/ developmental timing) -- could lead to evolution of novel
traits
3) Duplicated gene gains mutations → altered protein product could
perform valuable new function --- Gain mutations- get new product
-- could lead to evolution of novel traits
4) Mutation may prevent expression → Get pseudogene
3
• Gain % losses in # of gene copies (via duplication or deletion) has
contributed to interspecific differences
(do not memorize the diagram)
• Duplication of whole chromosome sets (genome) can contribute to
evolutionary differences
1) They are allowed
2) When you duplicate whole genome, then you have a lot of
opportunity to get new function or features
3) E.g., during early evolution of vertebrates → was a whole genome
duplication
• Genome wide duplication event have led to differences in number of
copies of some core development genes.
1) Along developing embryo – through pattern(order)
2) Human have 4 sets of Hox gens while Flies have only 1 set of Hox
genes
• Duplication of whole chromosome sets (genome)
1) Organization & content of Hox clusters in the mouse & region of
embryo in which they are expressed
• Multi cellular organisms are made up of numerous different tissues &
cells
Development
Fertilized egg → → → → → → → Adult
Many mitotic division
Document Summary
Pseudogene : it looks like a functional gene, but it don"t produce functional product. : d. one copy of a gene can perform the original function while other copies are available to take on new function. - could lead to evolution of novel traits: mutation may prevent expression get pseudogene. : b : these cell types contain the same genes, but different transcription factors. D,a (x) daughter cell have same gene with parent cell. Differences in coding sequence of pitx1 gene: 283 amino acids of the pitx1 protein are identical in marine & lake sticklebacks. 4: millions of genetic change aren"t necessary for diverse morphological change. Exception mass extinction & adaptive radiations. 5: evolutionary change is not constant over time, adaptive radiation rapid speciation & ecological diversification within a single lineage, often adaptive radiations shown as polytomies. = stay tuned, we are gathering more data so that we can resolve this.
